Viscous flow fields of side-by-side arranged two-dimensional floating bodies are numerically simulated by a Navier-Stokes equation solver. Two identical bodies with a narrow gap are forced to heave and sway motions. Square and rounded bilge hull forms are compared to find out the effects of vortex shedding on damping force. Wave height, force RAOs, added mass and damping coefficients including non-diagonal cross coefficients are calculated and a similarity between the wave height and force RAOs is discussed. CFD which can take into account of viscous damping and vortex shedding shows better results than linear potential theory.